Manufacture of a reactive trisodium phosphide



United States Patent O 3,397,038 MANUFACTURE OF A REACTIVE TRISODIUMPHOSPHIDE Alfred O. Minklei, Kenmore, N.Y., and Hans Z. Lecher,

Plainfield, N.J., assignors to Hooker Chemical Corporation, NiagaraFalls, N.Y., a corporation of New York No Drawing. Filed Nov. 30, 1964,Ser. No. 414,889 9 Claims. (Cl. 23-204) ABSTRACT OF THE DISCLOSURE Aprocess for producing alkali metal phosphides by reacting a finelydivided alkali metal with phosphorus at low temperatures in the presenceof a polycyclic aromatic hydrocarbon and an activating ether solvent.

This invention relates to the preparation of alkali metal phosphides andthe utilization of such alkali metal phosphides in the preparation ofphosphorus compounds.

It has heretofore been proposed to prepare alkali metal phosphides bythe reaction of phosphorus with the corresponding alkali metal attemperatures in the range of 750 degrees centigrade to 1,000 degreescentigrade.

An object of this invention is to prepare a reactive alkali metalphosphide by a low temperature process. Other objects of the inventionwill be apparent from the following description.

Ithas now been discovered that alkali metal phosphides can be made bythe low temperature reaction of phosphorus with a finely divided alkalimetal activated by a polycyclic aromatic hydrocarbon and an ethersolvent. The reaction product may thereafter be hydrolyzed by suitablehydrolyzing agents or it may be reacted with organic reactive halides toobtain the corresponding phosp'hines and corresponding phosphoniumcompounds.

Unexpectedly, the process of this invention yields highly reactivealkali metal phosphides. Additionally, it provides a novel method fortheir preparation. The reaction of phosphorus and an alkali metal doesnot proceed at low temperatures, while at elevated temperatures itproduces alkali metal phosphides which are unreactive towards organichalides and hydrolyze to yield phosphine contaminated by diphosphine.The alkali metal phosphides of this invention react readily with organichalides and hydrolyze to produce substantially pure phosphine.

In carrying out the process of this invention the alkali metal is firstdispersed in an inert liquid hydrocarbon dispersion medium boiling abovethe melting point of the alkali metal. Examples of suitable media aretoluene, xylene, mineral oil and the like. Dispersion of the alkalimetal may be accomplished by any suitable means. Generally, a devicecapable of imparting high shear, e.g., a rotating impeller, adispersator and the like, operating at a temperature which is maintainedabove the melting point of sodium, 97.5 degrees centigrade, but belowthe boiling point of the inert medium, may be effectively employed. Aconvenient temperature to effect the dispersion may be in the range of100 degrees centigrade to about 115 degrees centrigrade, buttemperatures from 100 to 300 degrees Centigrade are useful. Thedispersed alkali metal particles may have a diameter in the range offrom 0.2 micron to 60 microns. It is preferred to prepare particles inthe range of 0.5 micron to 40 microns and.

the most preferred are particles in the range of 0.5 micron to 20microns in diameter. Upon completion of the dispersion, which may takefrom 0.5 to 20 minutes of mixing, the dispersion medium is drained off.It is within the scope of this invention to employ the activatingsolvent, described below, instead of the liquid hydrocarbon dispersionmedium.

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A solvent mixture comprising an activating solvent selected from thepreferred group consisting of alkyloxy ethers and cyclic ethers, and aminor proportion of an aromatic hydrocarbon selected from the groupconsisting of condensed polycyclic hydrocarbons and noncondensedpolycylic aromatic hydrocarbons is then added to the alkali metaldispersion. It is apparent that under certain conditions, i.e., wherethe activating solvent described above is employed as a dispersionmedium, only a minor proportion of the aromatic polycyclic hydrocarboncatalyst may be added to the dispersed alkali metal. White or yellowphosphorus may then be added to the reaction mixture according to one ofthe following techniques: under inert conditions, e.g., under a nitrogenatmosphere; dissolved in a suitable solvent such as toluene, xylene,mineral oil, and the like; molten and added in a phosphorus carrier orvehicle such as tetrahydrofuran or toluene; or employing any othersuitable method. Red phosphorus cannot be used. Upon completion of thereaction, the alkali metal phosphide may be separated from the mixtureby filtration, or other solid-liquid separation technique, or it may bereacted directly with an appropriate reactant to produce the desiredphosphorus compound. It is to be understood that the process can becarried out batchwise, intermittently or continuously. Further, it is tobe understood that the invention is not limited to any particular typeof reactor for there are several convenient apparatuses for effectingthe process of this invention.

The alkali metals employed in the practice of this invention arepotassium, sodium, lithium, rubidium and cesium. The preferred alkalimetal is sodium.

As to the condensed polycyclic aromatic hydrocarbons, there can be usedthe condensed polycyclic aromatic hydrocarbons having 10 to about 32carbon atoms, the most preferred of these have 10 to 15 carbon atoms.Typical examples of these include naphthalene, anthracene, phenanthreneand the like. Of these, it has been found that naphthalene isparticularly suitable. In addition, non-condensed polycyclic aromatichydrocarbons having from 12 to about 32 carbon atoms may also beemployed effectively in the process of this invention. The mostpreferred of these have 12 to 19 carbon atoms. Typical examples of theseare: biphenyl, terphenyl, dinaphthyl, and the like.

Generally, the ethers used as activating solvents may be cyclic ethershaving from 4 to about 12 carbon atoms, the most preferred of these have4 to 8 carbon atoms. Typical examples of these are: tetrahydrofuran anddioxane. Of these, it has been found that tetrahydrofuran is particularly useful. Additionally, the ethers may be the alkyloxy ethers havingfrom 2 to about 20 carbon atoms. The most preferred of these have 2 to12 carbon atoms and contain at least one methoxy group. Examples ofthese are dimethyl ether of diethylene glycol, dimethyl ether oftriethylene glycol, dimethyl ether of tetraethylene glycol and the like.It is also within the scope of this invention to employ alkylatedglycols and polyhydric alcohols.

Sufficient activating solvent is employed to provide a convenientreaction mixture. Amounts in the range of 50:1 to about 200:1 based uponphosphorus have been satisfactorily employed. However, greater or lesseramounts of the activating solvent may be added, as desired.

The aromatic polycyclic hydrocarbon catalyst is utilized in molar ratiosbased on sodium employed. A molar ratio of aromatic hydrocarbon tosodium which may be utilized is in the range of 120.1 to about 1:80, themore preferred being 1:05 to 1:40 and the most preferred being 1:1 to1:15 on the basis mentioned.

Advantageously, the reaction of sodium, dispersed in the solventmixture, and phosphorus may be effected at temperatures ranging fromabout 10 degrees centigrade to 150 degrees centigrade, a preferred rangebeing 20 degrees centigrade to 100 degrees centigrade, and the 4Examples 1-15 The reactants, conditions and results of these examplesare set forth in Table I. The procedures followed are most preferred isa range of 30 degrees centigrade to 5 hereinafter-described. In areactor Vessel, an alkali metal 75 degrees centigrade. Further, theprocess of this indlspefsed uslng a q p Q and dlspelslon vention may becarried out at superatmospheric pressures, med111111- when Thedlspefslofl Ihedwm Was not 9 that atmospheric pressures andsubatmospheric pressures. could also be used as an activating solvent,the dlspersed Phosphorus is added to the reaction mixture in the alkalimetal was drained off. Subsequently, if required, process of theinvention in an amount substantially stoi- 10 the activating solvent wasadded to the dispersion, and, chiometrically equivalent to the sodiumemployed. 111 turn, the r atic polycyclic hydrocarbon was added Theproduct of the heretofore described process may the resultlng mlXtuTe-Thereafter, Phosphorus Was be hydrolyzed to produce phosphine. It is tobe underintroduced to the mixture and reacted therewtih.

TABLE I Example No 1 2 3 4 5 6 7 8 9 10 ll 12 13 14 15 Variables:

Reaction time, hours 4.3 1.0 1. 2.25 0.5 1.0 4.22 0.25 2.5 0.0 2.5 2.03.5 0.33 Reaction tern erature,

degrees centigr de -72 -71 5570 55 50-70 43-72 41-70 40-70 07-72 20-32135 130 101 101 101 White phosphorus addition time, hours 0.5 0.5 0.661.0 0.12 0.92 0.3 Sodium particles,microns 0.5-2 05-20 0. 5-20 0. 5-200.5-20 0.5-20 0. 5-20 0.5-20 0.5-20 0. 5-20 0.5-20 0. 5-20 0.5-20 0.5-20 0.5-20 Sodium/Naphthalene,

moles 5. 5 11 11 56 56 28 12 6. 8 11 5. 6 5, 6 5 6 Phosphorus Materialsin (Parts by Weight):

Sodium, parts 5.02 5. 02 5.02 5. 02 5. 02 5. 02 5. 02 5. 02 5. 02 5. 025. 02 5.02 5. 2 5,02 Phosphorus, parts 2.2 2.2 2.2 2.2 2.2 2.2 2.2 2.22.2 2.2 2.2 2.2 2.2 2 2 2.2 Naphthalene, parts 5 0 Tetrahydroturan,parts Anthracene, parts Biphenyl, parts Dioxanepal'ts 129.1 77.5 77 5Diethyl ether of diethylene glycol, parts 300 300 Yield NaaP (percent),based on phosphorus 47 76 90 88 86 83 82 90 00 72 54 75 91 s5 83Dissolved in 108.25 parts of toluene.

b Molten phosphorus under 13.3 parts of tetrahydroiuran or 12.9 parts ofli cihed over a two-minute period. stood that various hydrolyzing agentsmay be utilized. Examples of hydrolyzing agents include: water,alcohols, which may be employed in aqueous solutions, aqueous inorganichydrolyzing agents and aqueous organic hydrolyzing agents. The rate atwhich the hydrolyzing agent is added to the reaction product of thisinvention may vary considerably. However, by way of example, it may bedesirable to add the hydrolyzing agent in an aqueous solution dropwiseor in a steady stream.

In addition, the product of the above-described process may be reactedwith organic reactive halides selected from the group consisting ofalkyl and substituted alkyl halides having 1 to 20 carbon atoms, thepreferred having 1 to 10 carbon atoms; alkenyl and substituted alkenylhalides having 1 to 20 carbon atoms, the preferred having 1 to 10 carbonatoms; and aralkyl and substituted aralkyl halides having 6 to 18 carbonatoms, the preferred having 6 to 12 carbon atoms. Examples of thesecompounds are methyl chloride, butyl chloride, ethyl chloride,chloroacetonitrile, allyl chloride, benzyl chloride, methyl bromide,benzyl iodide, propyl iodide, ethyl bromide, allyl bromide, and thelike.

The reaction of the organic halide and the alkali metal phosphide may beeffected at temperatures in the range of 0 degree centigrade to about100 degrees centigrade, but temperatures from 0 degree centigrade to200- degrees centigrade are useful.

It is within the scope of this invention to effect the organic halidereaction as a step in the preparation of the alkali metal phosphide,whereby the need for the separation of alkali metal phosphide iseliminated. The recovery of the organic phosphorus compound, produced bythe reaction, may be accomplished by any suitable phase separationmethod, such as fractionation and the like. i

The following examples are given to illustrate the present invention andare not intended to limit the scope of the invention in any way. Alltemperatures are in degrees centigrade, and weights are in parts, partsare by weight, unless otherwise specified.

d Dissolved in 116.9 parts of toluene. Molten phosphorus under anatmosphere of nitrogen. t From completion of phosphorus addition.

In Examples 1, 2, 3 and 4, phosphorus was dissolved in toluene and addedto the reaction mixture comprising sodium and solvent; in Examples 5, 6,7 and 8, molten phosphorus under tetrahydrofuran or toluene was added tothe reaction mixture; in Examples 9 and 10, phosphrous was dissolved intoluene and added to the reaction mixture; and Examples 11, 12, 13, 14and 15, molten phosphorus, under an atmosphere of nitrogen, was added tothe reaction mixture.

Examples 9 and 10, show the results obtained using hydrocarbons such asanthracene and biphenyl, in place of naphthalene. The mole ratios ofalkali metal to hydrocafbon were effectively varied and producedefiicient resu ts.

Various ethers were used such as tetrahydrofuran, dioxane and dimethylether of diethylene glycol.

It is significant to note that temperatures in the range of 25 degreescentigrade and degrees centigrade were successfully employed.

Examples 11, 12, 13, 14 and 15, dispensed with the use of hydrocarbyldispersion medium for sodium and avoided the subsequent draining of saidmedium. Dioxane and dimethyl ether of ethylene glycol were substitutedand produced satisfactory results. When another alkali metal such aspotassium, lithium, rubidium or cesium is used in place of sodium,similar results are obtained.

EXAMPLE 16 A reactor vessel was charged with 5.02 parts of sodiumpreviously dispersed in 217 parts of toluene and drained of the excesssolvent, so as to produce sodium particles in the range of 0.5 micron to20 microns, and 355 parts of tetrahydrofuran containing 2.50 parts ofnaphthalene (1.0 molar proportion). The mixture was heated to 55 degreescentigrade, at which point 2.2 parts of phosphorus dissolved in 108parts of toluene were added to the stirred suspension over a period of0.66 hour. The mixture was stirred at 74 degrees centigrade for anadditional 1.25 hours. Thereafter, the resulting trisodium phosphide washydroylzed with water at 70 degrees centigrade, and

the evolved phosphine was measured by absorption in sodium hypobromite.

EXAMPLE 17 A typical reaction involving trisodium phosphide, prepared bythe process of this invention, and an aralkyl halide is illustrated. Areaction vessel was charged with 7.1 parts of trisodium phosphide (1.0molar proportion), prepared in tetrahydrofuran. The mixture was heatedto 71 degrees centigrade and 27.8 parts of benzyl chloride (3.0 molarproportions) were added to the stirred suspension over a period of 0.5hour. The mixture was then agitated for an additional 3.33 hours at 73degrees centigrade. After the reaction was complete, the excesstrisodium phosphide was filtred from the mixture and hydrolyzed withwater. The water and organic layers were separated and the organic layerwas distilled off. The residue in the reactor was subjected tosuccessive recrystallizations, whereupon a solid with a melting point of222.5 to 224 degrees centigrade was recovered. Literature value formelting point of tetrabenzyl phosphonium chloride is 225 degreescentigrade.

EXAMPLE 18 A typical reaction involving trisodium phosphide and an alkylhalide is disclosed by this example. .A reaction vessel 'was chargedwith parts of sodium particles having a diameter in the range of 0.5micron to 20 microns dispersed in toluene. The solvent toluene wasdrained off and 199.2 parts of tetrahydrofuran containing 10.0 parts ofnaphthalene was added. To this mixture were added 8.8 parts ofphosphorus dissolved in toluene and refluxed for a few hours. Uponcompletion of the reflux, 62 parts of ethyl chloride were added to themixture which was maintained at zero degrees centigrade. After standingovernight, the mixture had a layer of solids on the bottom with clearliquid on top. No phosphine was evolved when water was added to dissolvethe salt formed. The organic layer was separated and distilled. Theanalysis of the residue was 17.2 percent of phosphrous, indicating theformation of tetraethylphosphonium chloride. When the phosphoniumcompound is subjected to dry distillation, at temperatures above 200degrees and in vacuo, the corresponding phosphine is produced.

EXAMPLE 19 A reaction vessel was charged with 7.1 parts of trisodiumphosphide (1.0 molar proportion) suspended in 355 parts oftetrahydrofuran and 108 lparts of toluene. To the mixture, maintained at70 degrees centigrade, were added 26.5 parts of butyl chloride (3.0molar proportions). Completion of the reaction was evidenced by theabsence of phosphine when water was added.

EXAMPLE 20 The procedure of Example 19 was repeated, replacing the butylchloride with 20.1 parts of methyl chloride (4.8 molar proportions) andadded over a period of 0.88 hour. Water hydrolysis of the reactionmixture indicated that 84 percent of the trisodium phosphide hadreacted. When another organic halide such as methyl bromide, propyliodide, allyl bromide and the like is used in place of butyl chloride,similar results are obtained.

While there have been described various embodiments of the invention,the compositions and methods described are not intended to limit thescope of this invention, it being realized that changes therein andsubstitution of equivalents are possible. It is further intended thateach element recited in any of the following claims is to be understoodas referring to all equivalent elements for accomplishing substantiallythe same results in substantially the same or equivalent manner, theclaims covering the invention broadly in whatever from its principle maybe utilized.

What is claimed is:

1. A process for preparing an alkali metal phosphide comprising reactingphosphorus with a finely divided alkali metal dispersed in a solventcontaining an aromatic polycyclic hydrocarbon.

2. A process for preparing an alkali metal phosphide comprising reactingphosphorus with a finely divided alkali metal dispersed in a solventmixture comprising an activating ether solvent and an aromaticpolycyclic hydrocarbon, and separating the alkali metal phosphide fromthe reaction mixture.

3. A process in accordance with claim 2 wherein the dispersed finelydivided alkali metal comprises particles having a diameter in the rangeof 0.2 micron to 60 microns.

4. A process for preparing an alkali metal phosphide comprisingdispersing a finely divided alkali metal in a liquid hydrocarbondispersion medium boiling above the melting point of the alkali metal,removing the excess dispersion medium therefrom, adding a solventmixture comprising an activating ether solvent and a minor proportion ofan aromatic polycyclic hydrocarbon to the remaining dispersion, andintroducing phosphorus to said reaction mixture in an amountsubstantially stoichiometrically equivalent to the sodium employed,while maintaining the reaction temperature in the range of 10 degreescentigrade to 150 degrees centigrade.

5. A process for preparing an alkali metal phosphite comprising reactingphosphorus with a mixture which comprises alkali metal particles in therange of 0.2 micron to about 60 microns and a solvent mixture comprisingan activating ether solvent selected from the group consisting ofalkyloxy ethers and cyclic ethers, and a minor proportion of an aromatichydrocarbon selected from the group consisting of condensed polycyclichydrocarbons and noncondensed polycyclic aromatic hydrocarbons,maintaining the reaction temperature in the range of 10 degreescentigrade to 150 degrees centigrade, and separating the alkali metalphosphide formed.

6. A process in accordance with claim 5 wherein the dispersed alkalimetal is in the form of particles having a diameter in the range of 0.5micron to 20 microns.

7. A process for preparing an alkali metal phosphite comprising reactingphosphorus with a mixture which comprises alkali metal particles in therange of 0.5 micron to 20 microns and a solvent mixture comprising acyclic ether and a minor proportion of a condensed polycyclichydrocarbon having 10 to 15 carbon atoms, maintaining the reactiontemperature in the range of 10 degrees centigrade to 15 0 degreescentigrade, and thereafter separating the alkali metal phosphide formed.

8. A process in accordance with claim 7 wherein the naphthalene is usedin a molar proportion of 1:1 to 1:15 based on sodium employed.

9. A process for preparing trisodium phosphide comprising reactingphosphorus with a mixture which comprises sodium particles in the rangeof 0.5 micron and 20 microns and a solvent mixture comprisingtetrahydrofuran and a minor proportion of naphthalene, maintaining thereaction temperature in the range of 30 degrees centigrade to degreescentigrade and thereafter separating the trisodium phosphide formed.

References Cited UNITED STATES PATENTS 7/1965 Best 26093.7

OTHER REFERENCES OSCAR R. VERTIZ, Primary Examiner.

H. S. MILLER, Assistant Examiner.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No.3,397,038 August 13, 1968 Alfred O. Minklei et al.

It is certified that error appears in the above identified patent andthat said Letters Patent are hereby corrected as shown below:

"phosphrous" each Column 4, line 40 and column 5, lines 39 and 40,

lines 26 and 42,

occurrence, should read phosphorus Column 6, "phosphite", eachoccurrence, should read phosphide Signed and sealed this 31st day ofMarch 1970.

(SEAL) Attest:

WILLIAM E. SCHUYLER, JR.

Edward M. Fletcher, Jr.

Commissioner of Patents Attesting Officer

